When you have blood drawn, don't make a fist
When you have blood drawn, don’t make a fist
The next time you have blood drawn, don’t clinch your fist.
A new study, published in the Annals of Clinical Biochemistry, shows that the common practice of clinching then relaxing the hand when blood is drawn may raise potassium levels.
High potassium indicates potential heart or kidney problems, which are often treated with prescription drugs.
UK researchers examined the results of about 200,000 blood tests taken between 2002 and 2005. In 2003, phlebotomists (lab technicians who draw blood) were instructed to stop asking patients to clinch their fists. After the 2003 change in procedure, the number of blood tests with high potassium levels fell significantly.
Vanessa Thurlow, one of the authors of the study, told BBC News that in spite of the fact that doctors have known about this phenomena for many years, the fist-clenching procedure continues to be passed along from generation to generation. Some phlebotomists are taught to ask the patient to make a fist, and some are not.
Unfortunately, the clinched fist procedure will probably endure because the clinching action makes it easier to draw blood from patients whose veins are difficult to find.
Source:
“Warning Over Blood-Taking Method” BBC News, 7/26/08, news.bbc.co.uk
